The Northeast Heatwave

By: Dr. Jeff Masters , 9:08 AM GMT on July 07, 2010

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Hi, Dr. Rob Carver, filling in for Jeff while he's on vacation.

The most significant weather event in the US on July 6, 2010 didn't show up on any radar. The geostationary satellites didn't see it in their constant watch over the Earth's atmosphere. Instead, the tale of this event was told by the thermometers, because the heatwave in the Northeast was the most significant event for July 6, and it will likely be the most important weather story for July 7.

The heat wave covers Pennsylvania to Maine, but Tuesday's worst was centered over New York City. All six of the stations used by the New York NWS office for climate reports (Central Park, La Guardia, JFK, Islip, Bridgeport, and Newark) set or tied the daily high temperature record. Newark and Central Park both reached 103 degrees F.

How unusual is this heat wave?
Figures 1 and 2 show how warm the highs and lows are compared to 30 year averages. Unless you were at the Great Lakes, the Midwest and Northeast have highs well above normal, with 10-15+ degree F differences over the coastal cities of the Northeast. Using my gridded temperature data, the low for New York City was 6 degrees F above normal, which should happen 30% of the time (1.1 standard deviations away from normal). The high was roughly 20 degrees above normal, which should happen only 0.29% of the time (3.04 standard deviations away from normal). This is an unusually strong heat wave.

Why it's hot
Basically, it's because there is "the Bull of a high pressure ridge [over the NE US]" to quote the Mount Holly NWS office forecast discussion. The large ridge of high pressure is forcing air to slowly descend across the Northeast, preventing clouds from forming. Without no clouds and plenty of daylight, the Sun heats the ground which then heats the air.

When will it cool down?
That's an excellent question. A trough of low pressure off the coast will bring onshore winds to the Tri-State area and MA by Thursday, so they should cool down a bit. The southern part of the heat wave, DC and Philadelphia, will have to wait for a cold front to arrive from the Great Lakes sometime Saturday to get relief.

Population affected
As Figure 3 shows, heat advisories covered most of the urban areas of the northeastern US. By my calculations, over 32 million people were under a heat advisory. Different offices have different guidelines for heat advisories. The NWS office responsible for New York issues a heat advisory if the heat index will be above 95 deg. F for two or more days or if the index will be above 100 deg. F for any length of time.


Fig.1 Plot of the difference between maximum temperature (the high for the day) and average maximum temperature in degrees F for July 6.


Fig.2 Plot of the difference between minimum temperature (the low for the day) and average minimum temperature in degrees F for July 6.


Fig.3 Plot of the active heat advisories across the northeastern US for July 6.

Heatwave impacts
The predominant impact from heat waves is increased mortality. CDC estimates that over 8,000 people died during heat waves from 1979 to 2003. That's more than all of the deaths due to lightning, flooding, tornadoes, hurricanes, and earthquakes. The elderly, sick, poor, and very young face the worst of the effects of the heat. Wikipedia has an interesting article describing the Chicago Heat Wave of 1995, a modern heat wave with a large number of fatalities due to the heat.

Heatwave coping strategies
The Centers for Disease Control have some tips for dealing with the heat. In summary, drink plenty of water, spend time in air-conditioned buildings, and wear light-colored clothing.

Is this heat wave due to global warming?
Ah, the $64,000 question. In the absence of detailed analysis, it's hard to specify the exact cause for this heat wave, from a meteorological or climatological view point. However, events like this are consistent with research showing that heat waves are more likely with
global warming
. I like the metaphor of loaded dice, global warming is not specifically responsible for any heat wave, but it will make them happen more often.

Tropics
My thinking on Invest 96L is unchanged from this blog entry. In summary, I believe that 96L has a <50 % chance becoming a tropical cyclone before it makes landfall. If it does so, it will likely be near the coast when that happens. In any event though, the winds and waves it generates will likely disrupt oil spill recovery efforts. Also, I would expect a broad area of showers and 20+ mph winds will affect the Gulf coast somewhere from south Texas to Louisiana.

Next update
I'll have an update this afternoon to talk about the tropics.

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1237. Patrap
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Quoting StormW:
Upper level anticyclone now over 96L

Impressive.
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1235. KEEPEROFTHEGATE (Mod)
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1234. Patrap
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1232. Daveg
Quoting TexasHurricane:


oh ok. So what do you think this will become? If it does get a little stronger can it go a little furthur north?


Personally, I think at best a TS....going in somewhere around or just south of Corpus Christi.

Then again, these storms never cease to amaze and surprise me.
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Heavy topical rain here in Houston for the last couple hours..

almost no thunder and lightning.. very little wind .. just flat out heavy tropical rain
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Quoting TxMarc71:


Higher the cloud tops are the more severe the storm is.... thus the more potential for development...


Thanks...
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting hurricaster:
Awesome. Should be something to see.


Better get those fish shower curtains ready.
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Quoting StormW:


Yes...in fact, IR2 loop imagery indicates the LLC is pretty much under the convection...96L is becoming increasingly vertically stacked.
That's even more reason to upgrade the percentage at 8PM.
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Quoting StormW:


Yes...in fact, IR2 loop imagery indicates the LLC is pretty much under the convection...96L is becoming increasingly vertically stacked.


oh ok. So what do you think this will become? If it does get a little stronger can it go a little furthur north?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
I'm seeing low level inflow, circulation on visible. Right now in Corpus Christi, the pressure is 29.82 North East Winds @ 28 gusting to 40 with a squal that just came through. The winds have been out of the northeast since noon. I think we have a surface low at this point, especially given our pressure - 1009.7mb
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Quoting TexasHurricane:


meaning it is developing?


Higher the cloud tops are the more severe the storm is.... thus the more potential for development...
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Is there such thing as a goofcaster? Seem to have a few in our midst.
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Quoting StormW:
Got some overshooting tops going up.



meaning it is developing?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Statement as of 5:39 PM CDT on July 07, 2010

The National Weather Service in League City has issued an

* Urban and Small Stream Flood Advisory for...
central Harris County in southeast Texas...

* until 645 PM CDT

* at 538 PM CDT... National Weather Service Doppler radar indicated
very heavy rain was falling in and around the city of Houston.

Flooded roadways have been reported in the Bellaire area and in The
Heights as of 530 PM CDT.

Precautionary/preparedness actions...

Excessive runoff from heavy rainfall may cause elevated water levels
on small creeks... streams... and bayous. Additionally... ponding of
water will occur on highways... streets... and underpasses as well as
other poor drainage areas and low lying areas.

A Flood Watch remains in effect through 7pm Thursday for the warned
area.


Please report flooding to the County sheriff... local police... or
department of public safety and ask them to relay your report to the
National Weather Service.

Lat... Lon 2965 9556 3010 9573 3010 9567 3011 9565
3014 9550 3011 9549 3011 9543 3009 9539
3007 9534 3003 9529 3005 9525 3012 9516
2974 9503
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Awesome. Should be something to see.
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Quoting calder:


i appreciate that too, im just saying that there are actually very few people on this blog that give a balanced and non-bias prediction usually. I agree weak TS at worst case. Ppl this week been calling for cat 3 tho consistently...


REALLY??? I've been lurking everyday and have not seen ANYONE saying anything about 96l becoming a cat3?? You sure your reading the correct blog.. or maybe your just making stuff up for the sake of the argument?
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Quoting StormW:


Tropical Funnel: Def.

A device for pouring a tropical drink into ones person.


So the Brownsville WFO is spot on then! ;)
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1215. CJC111
Have to agree with calder. Usually, I'm lurking because I find the knowledge here and the weather fascinating. I do remember a couple of days ago there was more than 1 that called for a moderate to severe hurricane.
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Quoting calder:
i appreciate that too, im just saying that there are actually very few people on this blog that give a balanced and non-bias prediction usually. I agree weak TS at worst case. Ppl this week been calling for cat 3 tho consistently...

I haven't heard anyone say that 96L will become a CAT 3. (except for Taz but he is just kidding).
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Quoting KoritheMan:


None of the really knowledgeable people would say that. Are you sure you've been studying the right people?



I agree. I do not recall any of the knowledgeable bloggers calling for a Cat. 3.
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Quoting StormW:


Tropical Funnel: Def.

A device for pouring a tropical drink into ones person.
lmao ttf
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1210. Daveg
Quoting hurricaster:
Anybody have a guesstimate of the surface center location and current movement.


Last NHC fix was
Coordinates: 23.8N 93.6W

It hasn't moved just a ton since that last fix.
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1208. calder
Quoting KoritheMan:


None of the really knowledgeable people would say that. Are you sure you've been studying the right people?


maybe it was taz messing about, but i stick to what i said, it's been really apparent over the last few weeks.. Anyways, im out, bedtime in scotland. night
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Anybody have a guesstimate of the surface center location and current movement.
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Quoting nrtiwlnvragn:
From Brownsville WFO

FINALLY...THERE WILL BE A SMALL RISK FOR ISOLATED TROPICAL FUNNELS AND TORNADOES IN RAINBANDS DURING THE DAY ON THURSDAY ACROSS SOUTH TEXAS.


Tropical Funnels = ?
Tornado vortex that does not reach the ground?


Wonder if tropical funnels have little paper umbrellas in them :P
Member Since: March 10, 2010 Posts: 1 Comments: 7813
Quoting calder:


i appreciate that too, im just saying that there are actually very few people on this blog that give a balanced and non-bias prediction usually. I agree weak TS at worst case. Ppl this week been calling for cat 3 tho consistently...


When 96L was in the Caribbean, I didn't rule out a Hurricane for Texas/LA, I thought models were too south, which for the first circulation, they were. Now my thinking is South Texas. It hasn't been able to get going much, I have my doubts, but we'll see what tonight brings.
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Quoting calder:


i appreciate that too, im just saying that there are actually very few people on this blog that give a balanced and non-bias prediction usually. I agree weak TS at worst case. Ppl this week been calling for cat 3 tho consistently...


None of the really knowledgeable people would say that. Are you sure you've been studying the right people?
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1203. Drakoen
Quoting nrtiwlnvragn:


I think thats the P3. G-IV only reports dropsondes.


Yes
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1201. Daveg
Well it ain't purty... but it is starting to effect more and more of the gulf...

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1200. calder
Quoting CybrTeddy:


Oh come on, please tell me your kidding?


fraid not, it's how i see it
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Quoting calder:


i appreciate that too, im just saying that there are actually very few people on this blog that give a balanced and non-bias prediction usually. I agree weak TS at worst case. Ppl this week been calling for cat 3 tho consistently...


I've only seen Taz say that and he was just kidding around. We've all here have pretty much agreed that at most 96L will become a 45 mph TS.
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1197. calder
Quoting reedzone:


Ehh, I do have a slight gut feeling that I am wrong and this becomes a 40-50 mph. storm in the morning.. remember Erin form 2007? Though I look at the data, cooler TCHP and the time limit keeps my thoughts the same on 96L.


i appreciate that too, im just saying that there are actually very few people on this blog that give a balanced and non-bias prediction usually. I agree weak TS at worst case. Ppl this week been calling for cat 3 tho consistently...
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Quoting reedzone:


lol, I'm not mad or arguing, just answering your questing "which is it?"

We'll see what tonight brings, hey, I have some crow ready for me in the morning, along with my eggs ;)


That's the spirit son. :-)
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Quoting calder:


Stand your corner reed. There are bloggers here who have impressive met knowledge and input but are guilty of slightly inflating or exagerating forecasts on a daily basis


Oh come on, please tell me your kidding?
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Quoting HurricaneSwirl:


Eat the eggs first, I want you to taste that crow good :D


Indeed, it's defrosting, just in case.. ;)
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Quoting reedzone:


lol, I'm not mad or arguing, just answering your questing "which is it?"

We'll see what tonight brings, hey, I have some crow ready for me in the morning, along with my eggs ;)
LOL!
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Quoting calder:


Stand your corner reed. There are bloggers here who have impressive met knowledge and input but are guilty of slightly inflating or exagerating forecasts on a daily basis


Ehh, I do have a slight gut feeling that I am wrong and this becomes a 40-50 mph. storm in the morning.. remember Erin form 2007? Though I look at the data, cooler TCHP and the time limit keeps my thoughts the same on 96L.
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Quoting reedzone:


lol, I'm not mad or arguing, just answering your questing "which is it?"

We'll see what tonight brings, hey, I have some crow ready for me in the morning, along with my eggs ;)


Eat the eggs first, I want you to taste that crow good :D
Member Since: July 7, 2008 Posts: 2 Comments: 3237
1190. Daveg
Almost every model now has whatever 96L will become going in no farther south that Brownsville.

At least that's good news for the flood ravaged folks in Mexico.
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1189. calder
Quoting bakers:
heat waves, drouts,and floods have not increased, but global communications and reporting tecniques have.


Ah the GW sceptics are out...
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Quoting MiamiHurricanes09:
That's fine.


lol, I'm not mad or arguing, just answering your questing "which is it?"

We'll see what tonight brings, hey, I have some crow ready for me in the morning, along with my eggs ;)
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Quoting yonzabam:
It looks like 96L is going to cause serious flooding:

Link


Link


Indeed, and now with more rain on the way, that could "linger" for days. People sometimes forget that flooding is the great killer in any kind of tropical system. The wind is a sideshow, in terms of human fatalities.

If I lived in the Rio Grande valley, I think I'd be moving south, instead of north.
Member Since: August 27, 2009 Posts: 0 Comments: 525

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.